1. Field of the Invention
This invention relates to a catalyst component for .alpha.-olefin polymerization. Particularly it relates to a catalyst component for .alpha.-olefin polymerization, obtained by having a titanium compound supported on a novel carrier by reacting the compound with the carrier.
2. Description of the Prior Art
Supported type catalyst components for .alpha.-olefin polymerization have been studied over many years in order to, when used for the polymerization, improve the yield of poly-.alpha.-olefins per unit weight of transition metal catalyst components as much as possible, and also produce poly-.alpha.-olefins having good form, stereoregularity and other physical properties. Many of the carriers used for the catalyst components have been obtained by subjecting substances which are solid from the beginning to milling, mix-milling, mix-milling-and-burning or the like. In recent years, however, catalyst components for .alpha.-olefin polymerization or carriers for catalysts for the polymerization have been introduced which are obtained by mixing and reacting two kinds or more of liquid substances or a liquid substance or substances and a solid substance to obtain a solid substance (carrier), which is then reacted with a transition metal compound (see e.g. Japanese patent application laid-open Nos. Sho 55-29591 and Sho 55-135102(1980)). The steps of producing these catalyst components (or carriers) do not include either step of mix-milling or mix-milling-and-burning two kinds or more of solid raw materials. This fact is presumed to have aimed at improving the form of poly-.alpha.-olefins (particle diameter, particle size distribution and bulk density) indirectly affected by the form of the catalyst, by reducing the content of fine powder including solids which may form fine powder in the catalyst components. The direct object, however, is as in the past to maximize the yield of poly-.alpha.-olefins per the unit weight of the transition metal catalyst components obtained by utilizing the above-mentioned catalyst components, and also minimize the amount of atactic poly-.alpha.-olefin byproduced.
Further, Japanese patent application laid-open No. Sho 56-115301 (1981) discloses that as a Ti catalyst component used for .alpha.-olefin stereoregular polymerization process, a substance is used which is obtained by reacting a magnesium compound expressed by the general formula Mg(OR.sup.1).sub.n X.sup.1.sub.2-n with an aluminum halide expressed by the general formula AlX.sub.3.sup.2 and during or after the reaction, treating the reaction materials with an organic acid ester to obtain a carrier which is then reacted with a halogen-containing tetravalent Ti compound of the general formula Ti(OR.sup.3).sub.m X.sub.4-m.sup.3. Such an invention also aims at improving the catalyst activity and the stereoregularity of polymers.
The present inventors have made strenuous studies on a supported type catalyst component which has a higher activity and can produce a poly-.alpha.-olefin polymer having a higher stereoregularity than those of the above-mentioned prior inventions, and as a result have found that if a magnesium compound within a broader range of kinds of magnesium compounds than those disclosed in the above-mentioned Japanese patent application laid-open No. Sho 56-115301 (1981), expressed by the general formula MgR.sup.1 R.sup.2 (wherein R.sup.1 represents alkyl, aryl, alkoxy or aryloxy group and R.sup.2 represents alkyl, aryl, alkoxy, aryloxy group or halogen atom) is reacted with a complex compound of 1 one kind or more of compounds selected the group consisting of aluminum halides and aluminum compounds having the general formula AlR.sub.n.sup.3 X.sub.3-n (wherein R.sub.3 represents alkyl, aryl, alkoxy or aryloxy group, X represents halogen atom and n represents a number of 0.ltoreq.n&lt;2) with 2 an organic acid ester, and the resulting solid product (I) is used as a carrier, then reaction of this carrier with a liquid halogen-containing titanium compound within a far broader range than the range of those disclosed in the above-mentioned laid-open Japanese patent application i.e. those expressed by the general formula Ti(OR.sup.3).sub.m X.sub.4-m.sup.3, affords a catalyst component for .alpha.-olefin polymerization having a higher activity and capable of producing poly-.alpha.-olefins having a higher stereoregularity. Thus a first aspect of the present invention has been completed.
Further we have found that if this catalyst component of the first aspect of the present invention is preactivated by combining it with an organoaluminum compound and an .alpha.-olefin, it is possible to obtain a catalyst component which is superior in the storage stability and polymerization reproducibility to the above one (a second aspect of the present invention).
As is apparent from the foregoing, an object of the present invention is to provide a catalyst component for .alpha.-olefin polymerization, supported on a carrier which does not require mix-milling, and having a high activity and also capable of producing poly .alpha.-olefins having a high stereoregularity. Another object of the present invention is to provide a catalyst component having a carrier for which the raw material can be selected from among a broad range of raw materials and also capable of being easily prepared.